Process in which viscose silk is surjected to the action of caustic alkalis



Patented June 30, 1931 I ARGHIBALD Joni: HALL, or consumer, ENGLAND, ASSIGNOB TO THE SILVER SPRINGS BLEACHING- & DYEIHG comm LIMITED, OF TIKBE'RSBROOK, CONGL ETON,

anemia-1) PROCESS IN WHICH VISOOSE SILK IS SUBJECTED TO THE ACTION CAUSTIC ALKALIB 7 Ho lirawing. Application filed June 83, 1928, Serial No. 287,894, and in Great Britain July 9, 1827.

tion solutions of caustic potash at 15.'50

This invention, relates to processes for the treatment with a caustic alkali of textile materials such as yarns and fabrics, composed wholly or partly of desulfurized viscose.

It is known that when desulfurized viscose silk is exposed to the action of'solutions of We have now discover caustic soda it loses its soft feel and becomes harsh and brittle, this deleterious effect being generally. greater as the concentration of the caustic soda is increased. In consequence of this behaviour of. viscose silk towardscaustic soda it has bein found very difiicult to treat yarns and fa part1 of desulfurized viscose with rocesses whic require the use of caustic s a. One of such processes which is frequently desired to apply to cotton fabrics or yarns containingesulfurized viscose is the process of mercerization in which process caustic soda is employed as the mercerizi' agent.

that the behav iour 'of'desulfurized viscose silk towards solutions of caustic potash is quite different from its behaviour under'similar' circumstancestowards caustic soda, although this difference could not be foreseen without'exeriment. In particular we have found! that desulfurized viscose silk is-much less affected by caustic potash than by caustic soda and we have applied this discovery processes for treatment of yarns and fabrics com d wholly or partly of viscose silk and particularly to the mercerization of cotton materials containin desulfurized viscose silk, although it is to understood that it may also beapplied in the treatment with a caustic alkali of materials containing other fibres such as linen and which also contain desulfurized viscose. Our investigations of the actionof caustic potash on desulfurized viscose silk show that such action is influenced by the duration of the treatment, and also by the concentration and temperature of the solution of caustic potash employed. In general it has. been observed that caustic potash reduces the softness of handle of desulfurized viscose silk to a greater extent as the temperature of the caustic potash is decreased. It is therefore preferredio use for purposes of mercerizarics composed wholly or to various .cation occupy together about 80 seconds.

(1, and even higher temperatures. "The' deleterious action of caustic potash on the handle of desulfurized viscose silk also increases with the duration of treatment, so that it is preferred to carry out the operation of mercerization in the shortest time which allows the desired mercerization effects to be obtained. Although solutions of caustic potash of 70 Tw. appear to exert the'maximum deleterious action "on desulfurized viscose silk, the influence of concentration is small.

In applying this invention to the mercerization of cotton materials containing desulfurized viscose silk we adjust the conditions of duration, concentration, and tem erature such that the desulfurized viscose si k is not deleteriously effected whilst the cotton is satisfactprily mercerized..

The following is an example of the manner in which this invention is applied to the mercerization of cotton fabric containing desulfurized viscose silk which may be present in war or weft or both, it being clearly understood that this invention is not limited to the conditions stated therein.

' Ewamle Cotton fabric consisting of a'cotton warp and a desulfurized viscose weft is successively "impregnated with a solution of caustic potash of Tw. at 30 (3., stretched tothe desired width, washed'with cold or hot water while in the stretched condition, passed through a bath of dilute sul huric acid and afterwards thoroughly was ed and dried.

.The duration of the processes of impregnation with caustic potash, stretching, and washing up to the commencement of acidifi- In the resulting fabric, the cotton is well mercerlzed whilst the desulfurized viscosesilk has retained its original strength, lustre and softness of handle.

What I claim as my invention and desire to protect by Letters Patent is L'A process formercerizing textile fabrics containing desulfurized viscose silk con- I sisting in treating such materials with a solution of caustic potash under conditions of time, temperature, and concentration which are adjusted so that the cotton is nieicerized to the desired degree Whilst the desulfurized viscose silk is not deleteriousiy afi'ected.

2. A process for merceriz ing textile fabrics containing desulfurized viscose silk con sisting in treating such materials with a solution of caustic potash so that the cotton is mercerized to the desired degree Whilst the desulfurized Viscose siik is not deleteriously affected and finally subjecting the material to tension.

3. A process for mercerizing textile fabrics containing desuifurized viscose silk consisting in impregnating the material with a solution of caustic potash of 55 to 60 Tw. at a temperature'of over 15 C, stretching the material to the desired Width, Washing it with water While in the stretched condition,

passing through a loath of dilute sulphuric acid and finally washing and drying.

In testimony whereof I have hereunto set my hand.

ARCHIBALD JUHN HALL.

Leiaaoe 

